Power Feeding System, Power Feeding Apparatus, and Power Feeding Method

The present invention relates to a power feeding system, a power feeding apparatus, and a power feeding method.

Conventionally, there exists a power feeding device having first detecting means for detecting a direction of a power receiving device; and control means for controlling a radiation unit that radiates feeding power such that the radiation unit performs a first radiation, which radiates the feeding power wirelessly in a direction of the power receiving device detected by the first detecting means, and such that the radiation unit performs a second radiation, which radiates the feeding power wirelessly while changing a direction of radiating the feeding power within a predetermined range (see, for example, Patent Document 1).

Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-083648

Although the conventional power feeding device radiates the feeding power to the power receiving device by performing the first radiation and the second radiation, it does not disclose promptly setting phases capable of increasing received power at the power receiving device.

Therefore, an object is to provide a power feeding system, a power feeding apparatus, and a power feeding method capable of promptly setting phases for increasing received power at a power receiving device.

A power feeding system according to an embodiment of the present invention includes a power feeding apparatus, and a power receiving device configured to receive power transmission signals transmitted from the power feeding apparatus. The power feeding apparatus includes an array antenna including a plurality of antennas configured to transmit power, and a power transmission control unit configured to control phases of the power transmission signals that are to be transmitted from the plurality of antennas to the power receiving device, and control power transmission. The power transmission control unit is configured to: select one of a plurality of first antennas included in the plurality of antennas; and while transmitting a first power transmission signal having a fixed power transmission phase for a non-selected first antenna among the plurality of first antennas, perform, while selecting the plurality of first antennas one by one, both a first power transmission process of transmitting a first power transmission signal having a predetermined phase from the selected first antenna, and a second power transmission process of transmitting a first power transmission signal having an inverted phase obtained by inverting the predetermined phase from the selected first antenna. The power receiving device is configured to: determine a difference signal between a first combined signal, which combines the first power transmission signal having the predetermined phase and the first power transmission signal having the fixed power transmission phase, the first power transmission signals being both received from the plurality of first antennas in the first power transmission process; and a second combined signal, which combines the first power transmission signal having the inverted phase and the first power transmission signal having the fixed power transmission phase, the first power transmission signals being both received from the plurality of first antennas in the second power transmission process; and transmit the difference signal to the power transmission control unit. The power transmission control unit is configured to control phases of the plurality of first power transmission signals transmitted by the plurality of first antennas, based on a plurality of difference signals obtained by selecting each of the plurality of first antennas.

A power feeding system, a power feeding apparatus, and a power feeding method capable of promptly setting phases for increasing received power at a power receiving device can be provided.

Hereinafter, one or more embodiments to which a power feeding system, a power feeding apparatus, and a power feeding method of the present invention are applied will be described.

1 FIG. 300 300 100 50 50 300 100 50 50 50 50 50 is a diagram showing a power feeding systemaccording to the embodiment. The power feeding systemincludes a power feeding apparatusand a specific deviceA. The specific deviceA is an example of a power receiving device. In the following, description will be provided using an XYZ coordinate system. A plane view is an XY plane view. The power feeding systemmay also include the power feeding apparatusand a plurality of devices. The plurality of devicesinclude the specific deviceA and a plurality of non-specific devicesB other than the specific deviceA.

100 10 100 110 120 125 130 140 100 50 10 100 140 In an example, the power feeding apparatusis arranged in a regionof a large-scale facility such as a smart factory, a large-scale plant, a distribution center, or a warehouse. The power feeding apparatusincludes an array antenna, phase shifters, IC chips, a microwave generator, and a controller. The power feeding apparatusfeeds power to the plurality of devicesthat are present in the regionin a non-contact manner (microwave power feeding). The power feeding method according to the embodiment is a power feeding method that is implemented by the power feeding apparatus. In particular, the power feeding method is implemented by a process executed by the controller.

100 110 50 111 110 111 10 50 100 111 10 111 In the power feeding apparatus, the array antennatransmits power by beamforming, when the power is fed to an unspecified number of devices. A plurality of antenna elementsof the array antennacan transmit the power in power transmission phases that are specified by a power transmission control unit described later. When phases of power transmission signals output by the plurality of antenna elementsare fixed, standing waves are generated in the regiondue to one or more beams that are formed by the signals output from the plurality of antennas, and almost no power is fed to one or more deviceslocated at nodes of the standing waves. In order to avoid such a situation, the power feeding apparatusrandomly shifts the phases of the power transmission signals output from the plurality of antenna elementsover time, so that the nodes of the standing waves do not occur in a specific place for a long time. In other words, the nodes of the standing waves move within the region. The phases of the power transmission signals are shifted according to time slots. The power transmission signals are signals transmitted (radiated) from the antenna elements, and are RF (Radio Frequency) signals having predetermined power. As an example, a frequency of the power transmission signal is 918 MHz.

111 In this arrangement, power transmission that is performed using the beam, which is formed by randomly shifting the phases of the plurality power transmission signals output from the plurality of antenna elementsaccording to the time slots, is hereinafter referred to as random beamforming.

50 50 54 50 50 54 50 50 50 50 1 FIG. Also, among the plurality of devices, there may be a devicethat needs more received power to charge an internal battery. For example, such a device is a devicethat consumes more power than other devices, and in which the internal batteryhas less remaining power. Such a devicethat requires more power is referred to as the specific deviceA. In, one deviceat a certain time point is shown as the specific deviceA.

50 111 110 111 54 50 The specific deviceA receives power mainly from multiple antenna elementsincluded in an antenna subsetA, among the plurality of antenna elements. This is to charge the batteryof the specific deviceA earlier by performing more concentrated power transmission than random beamforming.

111 110 111 110 111 110 111 110 The multiple antenna elementsincluded in the antenna subsetA are examples of first antennas. Antenna elementsnot included in the antenna subsetA are examples of second antennas. Also, power transmission signals transmitted from the antenna elementsincluded in the antenna subsetA are examples of first power transmission signals, and power transmission signals transmitted from the antenna elementsnot included in the antenna subsetA are examples of second power transmission signals.

111 110 50 110 111 110 50 1 FIG. Phases for power transmission from the multiple antenna elementsincluded in the antenna subsetA to the specific deviceA are set for each frame. In, the antenna subsetA includes four antenna elements. The antenna subsetA, and phase shifting of the power transmission signals to the specific deviceA will be described later.

50 50 50 50 50 50 54 50 110 50 50 50 111 110 Among the plurality of devices, devices other than the specific deviceA are referred to as non-specific devicesB. All devicescan be specific devicesA depending on a situation. For the specific deviceA, when the batteryis charged sufficiently, concentrated power feeding to the specific deviceA from the antenna subsetA stops, and the specific deviceA becomes a non-specific deviceB. The non-specific deviceB receives power transmission by random beamforming from the antenna elementsincluding the antenna subsetA.

50 50 50 50 50 50 50 50 Also, the specific deviceA may be mobile in a manner such that the specific deviceA is mounted on a remotely manageable mobile device such as an automatic guided vehicle (AGV) or an autonomous mobile robot (AMR). The specific deviceA may have a configuration in which all devicesare mounted on such a mobile device and can become specific devicesA depending on a situation, or may have a configuration in which only a portion of all devicesis mounted on the above mobile device and can become specific devicesA depending on a situation. As an example, a manner in which the specific deviceA is mounted on a mobile device and is movable will be described below.

100 50 110 50 50 50 50 The power feeding apparatusis a power feeding apparatus capable of performing both power transmission by random beamforming to non-specific device(s)B and power transmission from the antenna subsetA to the specific deviceA. In the following, when the specific deviceA and the non-specific devicesB are not specifically distinguished, these devices will simply be referred to as devices.

2 FIG. 50 50 51 52 53 54 55 56 57 58 58 58 is a diagram showing a configuration example of the specific deviceA. The specific deviceA includes an antenna, a switch SW, a control unit, an RF/DC (Direct Current) conversion unit, a battery, an orthogonal detection unit, a calculation unit, an angle conversion unit, and a communication unit. The communication unitincludes an antennaA.

51 111 51 52 51 53 55 The antennais an antenna for receiving power from one or more antenna elements. The antennaoutputs the received power to the switch SW. The switch SW is switched by the control unitto switch a connection destination of the antennato either the RF/DC conversion unitor the orthogonal detection unit.

52 52 55 53 The control unitswitches the switch SW between an optimization period and a power feeding period in each frame. The control unitswitches the switch SW to connect to the orthogonal detection unitfor the optimization period, and switches the switch SW to connect to the RF/DC conversion unitfor the power feeding period.

52 55 56 57 58 140 100 During the optimization period, the control unitcauses the orthogonal detection unit, the calculation unit, the angle conversion unit, and the communication unitto perform a process to transmit data representing an angle that is obtained from a difference signal to the controllerof the power feeding apparatus.

52 54 111 51 The control unitperforms a charging control to charge the batterywith received power that is received from one or more antenna elementsvia the antennaduring the power feeding period.

54 51 54 52 53 55 56 57 58 The batteryis, for example, a secondary battery or a capacitor, and charges power fed from the antenna. The power charged to the batteryis used when the switch SW, the control unit, the RF/DC conversion unit, the orthogonal detection unit, the calculation unit, the angle conversion unit, and the communication unitoperate.

54 50 50 A load that consumes power may be connected to the battery. For example, the load may be a sensor that detects temperature, humidity, or the like. In this case, the devicecan be used as a sensor device. The load may be a power source such as a motor or an actuator, or the devicemay be a device that performs dynamic operations.

50 54 When the deviceis attached to a movable device, the power charged by the batterycan be used as power for driving a power source such as a motor of the movable device; or a control unit or the like.

53 51 54 The RF/DC conversion unitis a converter (conversion circuit) that converts the power transmission signal (RF signal) that is received power (received) by the antennainto DC power, and that outputs the DC power to the battery.

55 51 56 55 51 The orthogonal detection unitdemodulates the power transmission signal received by the antenna, extracts phase information, and outputs the phase information to the calculation unit. The phase information extracted by the orthogonal detection unitrepresents a phase of the power transmission signal received by the antenna.

56 55 The calculation unitperforms subtraction processing to determine a difference signal based on the phase represented by the phase information extracted by the orthogonal detection unit. The subtraction processing will be described later.

57 56 58 The angle conversion unitconverts the difference signal calculated by the calculation unitinto an angle in IQ coordinates, and outputs angle data representing the angle to the communication unit.

58 57 100 58 The communication unittransmits the angle data output from the angle conversion unit, to the power feeding apparatusvia an antennaA.

50 50 50 50 50 55 56 57 58 52 54 2 FIG. Although the configuration of the specific deviceA, among the plurality of devices, has been described with reference to, any devicethat does not become the specific deviceA and functions only as the non-specific deviceB, does not need to have the switch SW, the orthogonal detection unit, the calculation unit, the angle conversion unit, and the communication unit. In this case, the control unitonly needs to control the charging of the battery.

110 111 111 111 The array antennais an example of a two-dimensional antenna grid, and includes, as an example, antenna elementsarranged in a matrix. As an example, 256 antenna elementsinclude 16 elements in an X direction and 16 elements in a Y direction. The 256 antenna elementsare positioned on the XY plane.

111 130 130 111 111 110 111 140 50 50 50 111 110 50 50 50 111 110 111 111 Each antenna elementis connected to the microwave generatorvia one or more power transmission cablesA, and power in a microwave band is fed. Four antenna elements, which are selected as antenna elementsconstituting the antenna subsetA among the 256 antenna elementsby being controlled by the controller, transmit power in optimized phases toward the specific deviceA, but power is also secondarily fed to one or more non-specific devicesB that are located in the vicinity of the specific deviceA. Antenna elementsnot included in the antenna subsetA transmit power to one or more non-specific devicesB by random beamforming, but power is also secondarily fed to the non-specific devicesB from any antenna element(s) that are located relatively near the specific deviceA. The number of antenna elementsincluded in the antenna subsetA may be any number as long as there are multiple elements. Each antenna elementis a rectangular patch antenna in plan view. Each antenna elementmay have a ground plate held at a ground potential on a-Z direction side.

50 111 110 111 110 Further, in accordance with the movement of the specific deviceA, the antenna elementsconstituting the antenna subsetA are reviewed for each frame, and any antenna elementsto be included in the antenna subsetA are selected.

111 111 111 111 Each antenna elementis attached to a ceiling, a pillar, or the like of a large-scale facility such as the smart factory described above. A distance between antenna elementscorresponds to, for example, multiple wavelengths of the communication frequency of the antenna element. The communication frequency of the antenna elementis assumed to be a microwave band as an example, and is 918 MHz as an example.

1 FIG. 50 111 111 110 111 140 50 110 111 110 50 50 shows, as an example, a state in which the specific deviceA receives the power from the four antenna elementsamong the 256 antenna elementsincluded in the array antennaas described above. In this state, a set of antenna elementsselected by the controllerto transmit the power to the specific deviceA is referred to as the antenna subsetA. Antenna elementsnot included in the antenna subsetA transmit power by random beamforming while shifting phases of power transmission signals according to time slots, and the power transmitted by the random beamforming is received by non-specific devicesB, but is also received secondarily by the specific deviceA.

120 111 111 130 111 120 125 1 FIG. The phase shiftersare connected to respective antenna elementsin a 1-to-1 relationship, and each of phase inserted a the shifters is between corresponding antenna elementand the transmission cableA. In, for convenience of explanation, one antenna element, the phase shifter, and the IC chipare enlarged.

120 130 130 111 120 125 125 140 125 The phase shiftershifts a power transmission phase of the power transmitted from the microwave generatorvia the power transmission cableA, and outputs the resulting power to the antenna element. The phase shifteris an example of a phase adjusting unit. The IC chipincludes a measurement unit that measures RSSI (Received Signal Strength Indicator) of the received power, and includes a BLE communication unit. The IC chiptransmits a beacon signal including data representing a measured RSSI value to the controller. The communication unit of the IC chiphas an antenna for BLE communication.

130 120 130 100 130 The microwave generatoris connected to 256 phase shiftersand supplies microwaves at a predetermined power level. The microwave generatoris an example of a radio wave generator. The frequency of the microwave is 918 MHz as an example. Although a case where the power feeding apparatusincludes the microwave generatoris described, it is not limited to microwaves, and any radio waves of a predetermined frequency may be used.

140 The controlleris an example of a control unit, and is a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and a non-volatile memory, and the like. As an example, discrete wavelet multitone (DWMT) can be used.

140 140 50 The controllerhas an antennaA and receives a beacon signal in which angle data is written from the specific deviceA.

140 111 110 120 130 111 110 111 110 120 The controllerperforms a selection control (ranking processing) of antenna elementsincluded in the antenna subsetA, a phase control of the 256 phase shifters, and a power output control of the microwave generator. The phase control of power transmission signals of the antenna elementsincluded in the antenna subsetA, and the phase control of power transmission signals by random beamforming of antenna elementsnot included in the antenna subsetA are implemented by the phase control of the phase shifters.

3 FIG. 140 140 141 142 143 144 141 142 143 140 144 140 is a diagram showing the configuration of the controller. The controllerincludes a main control unit, a subset selection unit, a power transmission control unit, and a memory. The main control unit, the subset selection unit, and the power transmission control unitrepresent functions of one or more programs that are executed by the controller, as functional blocks. The memoryfunctionally represents a memory in the controller.

141 140 142 143 The main control unitis a processing unit that supervises processing of the controller, and executes processing other than that executed by the subset selection unitand the power transmission control unit.

142 50 111 142 111 110 7 FIG. The subset selection unitis an example of an antenna selection unit. When a difference signal is transmitted from the specific deviceA in each frame, and RSSI values are acquired in a case where difference signals are received by all antenna elements, the subset selection unitselects multiple antenna elementsincluded in the antenna subsetA based on RSSI value ranking. Details of such a selection method based on the RSSI value ranking will be described later with reference to.

143 111 111 143 111 10 50 1 FIG. The power transmission control unitperforms a power transmission control to transmit power from all the antenna elements. When power transmission is performed from all the antenna elements, the power transmission control unitperforms the power transmission control by random beamforming in which phases of the power transmission signals from all the antenna elementsare randomly set and the phases are randomly shifted for each time slot (random mode). In this arrangement, one or more positions of standing waves of any power transmission signals in the region(see) can be prevented from being temporally fixed, and thus all devicescan receive power relatively uniformly.

110 142 143 When the antenna subsetA is constructed using the subset selection unit, the power transmission control unitperforms an optimization process during an optimization period in each frame, and performs a power feeding process during a power feeding period in each frame. The optimization process during the optimization period, and the power feeding process during the power feeding period will be described later.

144 141 142 143 144 The memorystores data, programs, and the like used when the main control unit, the subset selection unit, and the power transmission control unitperform processing. Data representing a given phase of the power transmission signal in each time slot is also stored in the memory.

4 FIG. shows an example of a frame structure. As an example, a frame period is 50 ms. The frame includes the optimization period and the power feeding period. The power feeding period is set after the optimization period.

111 110 111 111 51 50 50 The optimization period is a period during which the optimization process is performed to optimize phases (power transmission phases) of power transmission signals transmitted by multiple antenna elementsincluded in the antenna subsetA. The optimizing of the phases of the power transmission signals transmitted by the multiple antenna elementsmeans to align phases (power reception phases) in which the power transmission signals transmitted by the multiple antenna elementsare received by the antennaof the specific deviceA. If the power reception phases of the multiple power transmission signals are aligned, the received power of the specific deviceA can be maximized. The above phase alignment is not limited to a case where phases are completely identical, but also includes a case where the phases are substantially equivalent to being completely identical. This is because in some cases, it is not easy to align the phases strictly, and for example, if phase deviation is within about ±5%, it is considered sufficiently aligned.

111 110 111 110 111 110 111 110 In the optimization period, phases of power transmission signals transmitted by multiple antenna elementsnot included in the antenna subsetA are each set at a fixed value. When the power transmission phases of the antenna elementsincluded in the antenna subsetA are optimized, power transmission phases of the multiple antenna elementsnot included in the antenna subsetA are fixed so as to prevent the influence of the power transmission signals transmitted from the multiple antenna elementsnot included in the antenna subsetA.

111 111 111 110 111 110 111 The power feeding period is a period in which the power feeding process of transmitting power transmission signals from multiple antenna elementsis performed in a state where phases of the power transmission signals transmitted by the multiple antenna elementsare optimized by the optimization process in the optimization period. During the power feeding period, m beamforming is performed for the multiple antenna elementsincluded in the antenna subsetA in a state of maintaining the relationship between a plurality of power transmission phases that are determined by the optimization process in an optimization section within the same frame. Also, for multiple antenna elementsnot included in the antenna subsetA, random beamforming is performed without setting any relationship between power transmission phases of the multiple antenna elements.

111 110 1 4 1 The four antenna elementsincluded in the antenna subsetA are distinguished as antenna elements mto m, and the optimization of the power transmission phase for an antenna element mwill be described.

2 4 1 1 50 111 51 50 55 During optimization, power transmission is performed together with antenna elements mto min either a currently set phase for the antenna element mor in a specific phase (for example, 0 degrees). A signal received by the specific deviceA is a signal obtained by combining power transmission signals from all antenna elementsat the antennaof the specific deviceA. When describing by extracting the contribution from the antenna element min time slot k, a power transmission signal r(k), which is converted to a baseband signal (demodulated by the orthogonal detection unit) by a regenerated carrier through signal conversion from a radio frequency into baseband (orthogonal detection), is expressed by the following equation (1).

m1 1 m1 m1 1 1 2 4 1 51 51 110 111 110 111 51 Here, A is the entire antenna set, S is the antenna subset, φ(k) in the first term is the power transmission phase set in the antenna element m, PRis received power, and ξis phase displacement between the antenna element mand the antenna, and is a remainder (fractional part) when a distance between the antenna element mand the antennais divided by the wavelength. The second term relates to a signal component received from antenna elements mto mother than the antenna element min the antenna subsetA. The third term relates to a signal component received from antenna elementsnot included in the antenna subsetA. During the optimization process, a temporal variation in the phase between antenna elementsand the antennais assumed to be negligibly small.

1 2 4 m1 1 110 111 110 In subsequent time slot k+1, power transmission is performed with a power transmission phase from the antenna element mthat is shifted by 180 degrees (π), that is, with the phase inverted, together with other antenna elements mto mincluded in the antenna subsetA and antenna elementsnot included in the antenna subsetA. A power transmission phase φ(k+1) for the antenna element min the time slot k+1 is expressed by the following equation (2).

m1 2 4 110 111 110 Here, when the power transmission phase φ(k+1) exceeds 360 degrees, it is reduced to a range of 1 to 360 degrees by modulo operation. Since power transmission phases for the other antenna elements mto mincluded in the antenna subsetA and the antenna elementsnot included in the antenna subsetA are not changed, only the power transmission phase for the antenna element m; changes (inverts).

50 51 111 1 The specific deviceA on a receiving side similarly converts a signal from the radio frequency to the baseband signal (orthogonal detection). A power transmission signal r(k+1) received in the time slot k+1 is a signal obtained by combining, at the antenna, the power transmission signals transmitted from all antenna elements, as in the time slot k. When describing by extracting the contribution from the antenna element m, the power transmission signal r(k+1) is expressed by the following equation (3).

111 1 1 The power transmission signal received in the time slot k+1 is subtracted from the power transmission signal received in the time slot k. Since the antenna elementsother than the antenna element mtransmit power in the same power transmission phase over two consecutive time slots k and k+1, the resulting power units are canceled, and the difference signal is expressed by the following equation (4), and only a signal component from the antenna element mremains.

1 1 1 140 A power transmission phase (ξm+φm(k)) of the power transmission signal transmitted from the antenna element mis detected as shown in the following equation (5), and the resulting value is transmitted to the controller.

140 1 The controllercontrols the power transmission phase for the antenna element mso as to either negate the received power transmission phase or to achieve a specific phase. The power transmission phase determined by the phase control is reflected in the power feeding period after time slot k+5.

1 m1 m1 1 m1 51 50 When the power is transmitted from the antenna element min power transmission phase φ(k+5) after time slot k+5, a power reception phase φ(k+5) in which the power transmission signal transmitted the antenna element mis received by the antennaof the specific deviceA is aligned in an in-phase axis direction, and for example, the power reception phase φ(k+5) is set at zero in the following equation (7).

5 FIG. 5 FIG. 5 FIG. 110 111 111 110 110 111 is a diagram for describing an example of the optimization process.shows the optimization period, the power feeding period, and time slots in one frame. In this figure, as an example, it is assumed that the antenna subsetA includes four antenna elements. The optimization process includes a number of time slots equal to the number of antenna elementsincluded in the antenna subsetA plus 1. In, since the antenna subsetA includes the four antenna elements, the time slots in the optimization period are five slots (k to k+4). The power feeding period starts from time slot k+5 and is longer than the optimization period, but the power feeding period is simplified in this description.

111 110 111 110 1 4 1 The four antenna elementsincluded in the antenna subsetA are distinguished as antenna elements mto m. Multiple antenna elements(each of which is an example of a non-selected first antenna) not included in the antenna subsetA are donated as antennas n, . . . .

1 1 2 4 2 4 1 4 1 4 In time slot k, the power transmission phase for the antenna element mis set at φm, and the power transmission phases for the antenna elements mto mare set at φmto φm. In this state, power transmission signals are transmitted from the antenna elements mto m. Note that φmto φmare arbitrary power transmission phases.

1 1 2 4 2 4 1 4 1 1 1 2 4 2 4 In time slot k+1, the power transmission phase for the antenna element mis changed to φm+π, and the power transmission phases for the antenna elements mto mare set at φmto φm. In this state, power transmission signals are transmitted from the antenna elements mto m. The power transmission phase φm+π for the antenna element mthat is changed in the time slot k+1 is an inverted phase that is obtained by inverting the power transmission phase φmin the time slot k. In the time slots k to k+1, the power transmission phases for the antenna elements mto mare fixed at φmto φm.

1 1 2 2 3 4 3 4 1 4 2 2 2 1 1 3 4 3 4 In time slot k+2, the power transmission phase of the antenna element mis set at φm+π, the power transmission phase of the antenna element mis changed to φm+π, and the power transmission phases of the antenna elements mand mare set at φmand φm. In this state, the power transmission signals are transmitted from the antenna elements mto m. The power transmission phase φm+π of the antenna element mchanged in time slot k+2 is an inverted phase obtained by inverting the power transmission phase φmin the time slots k to k+1. In time slots k+1 and k+2, the power transmission phase of the antenna element mis fixed at φm+π. In time slots k to k+2, power transmission phases of the antenna elements mand mare fixed at φmand φm.

1 1 2 2 3 3 4 4 1 4 3 3 3 1 1 2 2 4 4 In time slot k+3, the power transmission phase for the antenna element mis set at φm+π, the power transmission phase for the antenna element mis set at φm+π, the power transmission phase for the antenna element mis changed to φm+π, and the power transmission phase for the antenna element mis set at φm. In this state, power transmission signals are transmitted from the antenna elements mto m. The power transmission phase φm+π for the antenna element mchanged in the time slot k+3 is an inverted phase that is obtained by inverting the power transmission phase φmin time slots k to k+2. In the time slots k+1 to k+3, the power transmission phase for the antenna element mis fixed at φm+π, and in the time slots k+2 and k+3, the power transmission phase for the antenna element mis fixed at φm+π. In the time slots k to k+3, the power transmission phase for the antenna element mis fixed at φm.

1 1 2 2 3 3 4 4 1 4 4 4 4 1 1 2 2 3 3 In time slot k+4, the power transmission phase for the antenna element mis set at φm+π, the power transmission phase for the antenna element mis set at φm+π, the power transmission phase for the antenna element mis set at φm+π, and the power transmission phase for the antenna element mis changed to φm+π. In this state, power transmission signals are transmitted from the antenna elements mto m. The power transmission phase φm+π for the antenna element mthat is obtained by making changes in the time slot k+4 is an inverted phase obtained by inverting the power transmission phase φmin the time slots k to k+3. In the time slots k+1 to k+4, the power transmission phase for the antenna element mis fixed at φm+π, and in the time slots k+2 to k+4, the power transmission phase for the antenna element mis fixed at φm+π. In the time slots k+3 and k+4, the power transmission phase for the antenna element mis fixed at φm+π.

1 1 1 1 1 1 1 1 1 As described above, during the optimization period of the time slots k to k+4, the optimization process is performed on the power transmission phase for the antenna element min the time slots k and k+1, and from the time slot k+1 onward, the power transmission phase for the antenna element mis fixed at φm+π. The optimization process of the time slot k, in which the power transmission phase for the antenna element mis set at φmto transmit the power transmission signal, is an example of a first power transmission process for the antenna element m, and the optimization process of the time slot k+1, in which the power transmission phase for the antenna element mis set at φm+π to transmit the power transmission signal, is an example of a second power transmission process for the antenna element m. The optimization period in which the first power transmission process and the second power transmission process are performed is an example of a preparation period.

2 2 2 2 2 2 2 2 2 2 2 In the optimization period of the time slots k to k+4, the optimization process is performed on the power transmission phase for the antenna element min the time slots k+1 and k+2. In the time slots k to k1, the power transmission phase for the antenna element mis fixed at φmand from the time slot k+2 onward, the power transmission phase for the antenna element mis fixed at φm+π. The optimization process in the time slot k+1, in which the power transmission phase for the antenna element mis set at φmto transmit the power transmission signal, is an example of a first power transmission process for the antenna element m, and the optimization process in the time slot k+2, in which the power transmission phase for the antenna element mis set at φm+π to transmit the power transmission signal, is an example of a second power transmission process for the antenna element m.

3 3 3 3 3 3 3 3 3 3 In the optimization period of the time slots k to k+4, the optimization process is performed on the power transmission phase for the antenna element min the time slots k+2 and k+3. In the time slots k to k2, the power transmission phase for the antenna element mis fixed at φm, and from the time slot k+3 onward, the power transmission phase for the antenna element mis fixed at φm+π. The optimization process in the time slot k+2, in which the power transmission phase for the antenna element mis set at oms to transmit the power transmission signal, is an example of a first power transmission process for the antenna element m, and the optimization process in the time slot k+3, in which the power transmission phase of the antenna element mis set at φm+π to transmit the power transmission signal, is an example of a second power transmission process for the antenna element m.

4 4 4 4 4 4 4 4 4 4 4 In the optimization period of the time slots k to k+4, the optimization process is performed on the power transmission phase for the antenna element min the time slots k+3 and k+4. In the time slots k to k3, the power transmission phase for the antenna element mis fixed at φm, and in the time slots k+4, the power transmission phase for the antenna element mis changed to φm+π. The optimization process in the time slot k+3, in which the power transmission phase for the antenna element mis set at φmto transmit the power transmission signal, is an example of a first power transmission process for the antenna element m, and the optimization process in the time slot k+4, in which the power transmission phase for the antenna element mis set at φm+π to transmit the power transmission signal, is an example of a second power transmission process for the antenna element m.

1 4 111 110 111 111 110 111 111 In the power feeding period, the power transmission phases for the antenna elements mto mare set at optimized power transmission phases, and random beamforming is performed while maintaining the relationship between four optimized power transmission phases. Also, in the optimization period, for multiple antenna elements(each of which is an example of a non-selected first antenna) not included in the antenna subsetA, the phase for each of the multiple antenna elementsis fixed at an arbitrary phase. In the power feeding period, for the multiple antenna elementsnot included in the antenna subsetA, random beamforming is performed for each of the multiple antenna elementswithout having any relationship between the power transmission phases for the multiple antenna elements. The power feeding period is an example of the power transmission period.

6 6 FIGS.A toE 50 50 1 4 are diagrams for describing the power reception phase of the power transmission signal received by the specific deviceA. The I-axis is a real axis, and the Q-axis is an imaginary axis. Four vectors (1) to (4) represent power transmission signals received by the specific deviceA from the antenna elements mto min vector form.

1 4 1 4 4 1 4 51 It is assumed that the power transmission phases for antenna elements mto mare φmto φm, respectively, and that remainders (fractional parts) obtained by dividing distances between the antenna elements m; to mand the antennaby a wavelength are ξmto ξm, respectively.

6 FIG.A 6 FIG.A 50 1 4 1 1 2 2 3 3 4 4 As shown in, power transmission phases of the power transmission signal received by the specific deviceA from the antenna elements mto min the time slot k are ξm+φm, ξm+φm, ξm+φm, and ξm+φm, respectively. The four vectors (1) to (4) are as shown in.

50 1 4 1 1 2 2 3 3 4 4 6 FIG.A In the time slot k+1, the power reception phases of the power transmission signals received by the specific deviceA from the antenna elements mto mare ξm+φm+π, ξm+φm, ξm+φm, and ξm+φm, respectively. The four vectors (1) to (4) are as shown in, and the vector (1) is oriented in an opposite direction compared to the time slot k.

56 57 When the four vectors (1) to (4) in the time slot k+1 are subtracted from the four vectors (1) to (4) in the time slot k, the vectors (2) to (4) are eliminated, and only a vector (1A), which has twice the magnitude of the vector (1), remains as the difference. A signal representing the vector (1A) is a difference signal, and is obtained by the calculation unitthrough subtraction processing. An angle of the vector (1A) with respect to the I-axis is α1. The angle α1 is obtained by the angle conversion unit. The four vectors (1) to (4) in the time slot k are an example of a first combined signal, and the four vectors (1) to (4) in the time slot k+1 are an example of a second combined signal.

6 FIG.B 6 FIG.B 50 1 4 1 1 2 2 3 m 4 4 As shown in, power reception phases of the power transmission signals received by the specific deviceA from the antenna elements mto min the time slot k+1 are ξm+φm+π, ξm+φm, ξm+φm, and ξm+φm, respectively. The four vectors (1) to (4) are as shown in.

50 1 4 1 1 2 2 3 3 4 4 6 FIG.B The power reception phases of the power transmission signals received by the specific deviceA from the antenna elements mto min the time slot k+2 are ξm+φm+π, ξm+φm+π, ξm+φm, and ξm+φm, respectively. The four vectors (1) to (4) are as shown in, and the vector (2) is oriented in the opposite direction compared to the time slot k+1.

56 57 When the four vectors (1) to (4) in the time slot k+2 are subtracted from the four vectors (1) to (4) in the time slot k+1, the vectors (1), (3), and (4) are eliminated, and only a vector (2A), which has twice the magnitude of the vector (2), remains as the difference. A signal representing the vector (2A) is a difference signal, and is obtained by the calculation unitthrough subtraction processing. An angle of the vector (2A) with respect to the I-axis is α2. The angle α2 is obtained by the angle conversion unit. The four vectors (1) to (4) in the time slot k+1 are an example of a first combined signal, and the four vectors (1) to (4) in the time slot k+2 are an example of a second combined signal.

6 FIG.C 6 FIG.C 50 1 4 1 1 2 2 3 3 4 4 As shown in, power reception phases of the power transmission signals received by the specific deviceA from the antenna elements mto min the time slot k+2 are ξm+φm+π, ξm+φm+π, ξm+φm, and ξm+φm, respectively. The four vectors (1) to (4) are as shown in.

50 1 4 1 1 2 2 3 3 4 4 6 FIG.C The power reception phases of the power transmission signals received by the specific deviceA from the antenna elements mto min the time slot k+3 are ξm+φm+π, ξm+φm+π, ξm+φm+π, and ξm+φm, respectively. The four vectors (1) to (4) are as shown in, and the vector (3) is oriented in the opposite direction compared to the time slot k+2.

56 57 When the four vectors (1) to (4) in the time slot k+3 are subtracted from the four vectors (1) to (4) in the time slot k+2, the vectors (1), (2), and (4) are eliminated, and only a vector (3A), which has twice the magnitude of the vector (3), remains as the difference. A signal representing the vector (3A) is a difference signal, and is obtained by the calculation unitthrough subtraction processing. An angle of the vector (3A) with respect to the I-axis is α3. The angle α3 is obtained by the angle conversion unit. The four vectors (1) to (4) in the time slot k+2 are an example of a first combined signal, and the four vectors (1) to (4) in the time slot k+3 are an example of a second combined signal.

6 FIG.D 6 FIG.D 50 1 4 1 1 2 2 3 3 4 4 As shown in, power reception phases of the power transmission signals received by the specific deviceA from the antenna elements mto min the time slot k+3 are ξm+φm+π, ξm+φm+π, ξm+φm+π, and ξm+φm, respectively. The four vectors (1) to (4) are as shown in.

50 1 4 1 1 2 2 3 3 4 4 6 FIG.D The power reception phases of the power transmission signals received by the specific deviceA from the antenna elements mto min the time slot k+4 are ξm+φm+π, ξm+φm+π, ξm+φm+π, and ξm+φm+π, respectively. The four vectors (1) to (4) are as shown in, and the vector (4) is oriented in the opposite direction compared to the time slot k+3.

56 57 When the four vectors (1) to (4) in the time slot k+4 are subtracted from the four vectors (1) to (4) in the time slot k+3, the vectors (1) to (3) are eliminated, and only a vector (4A), which has twice the magnitude of the vector (4), remains as the difference. A signal representing the vector (4A) is a difference signal, and is obtained by the calculation unitthrough subtraction processing. An angle of the vector (4A) with respect to the I-axis is α4. The angle α4 is obtained by the angle conversion unit. The four vectors (1) to (4) in the time slot k+3 are an example of a first combined signal, and the four vectors (1) to (4) in the time slot k+4 are an example of the second combined signal.

57 58 100 When the angle conversion unitobtains the angles α1 to α4 for the vectors (1) to (4) as described above, the communication unittransmits angle data representing the angles α1 to α4 to the power feeding apparatusat the last timing of the time slot k+4.

143 6 FIG.E 6 FIG.E The power transmission control unitadjusts the phases for the vectors (1) to (4) to adjust the angles α1 to α4 in the time slot k+5. As a result, directions of the vectors (1) to (4) can be aligned as shown in. In, the directions of the vectors (1) to (4) are along the I-axis as an example, but may have an angle greater than 0 degrees with respect to the I-axis.

50 In this arrangement, the angles for the vectors (1) to (4) can be aligned. That is, the received power of the specific deviceA can be maximized.

1 4 111 110 111 In the power feeding period after the time slot k+5, random beamforming is performed while maintaining the relationship between the four power transmission phases for the antenna elements mto m, such that the angles for vectors (1) to (4) are aligned. For multiple antenna elementsnot included in the antenna subsetA, random beamforming is performed without setting any particular relationship between the power transmission phases for the multiple antenna elements.

100 111 125 142 111 110 111 The power feeding apparatusreceives signals including angle data via all antenna elements, and the IC chipmeasures RSSI of the received power. The subset selection unitselects antenna elementsincluded in the antenna subsetA by performing ranking based on the RSSI of the signals including the angle data that are received by all the antenna elements.

7 FIG. 7 FIG. 111 111 is a diagram showing an example of a ranking result.shows the ranking (in descending order of RSSI), RSSI (dBm), and antenna index. As an example, one or more antenna elementsare selected up to −15 dB relative to the antenna elementwith the highest RSSI.

7 FIG. 111 111 111 110 110 111 111 110 111 111 In, as an example, the antenna elementwith the antenna index No. 5 has the highest RSSI of −50.0 dBm, and four antenna elementsranked up to the fourth place, up to a 15 dB drop (up to −50.0-15 dB) relative to −50.0 dBm, are selected as antenna elementsincluded in the antenna subsetA. In this example, a case where the antenna subsetA includes the four antenna elementsis described, but since the number of antenna elementsincluded in the antenna subsetA in each frame is determined by the number of antenna elementswithin the 15 dB drop from the highest RSSI, the number of antenna elementsmay be either more or less than four.

8 FIG. 8 FIG. 140 50 300 140 50 300 is a flowchart showing an example of processing executed by the controllerand the specific deviceA in the power feeding system. Although the controllerand the specific deviceA perform processing separately, the processing will be described as a series of processing in the power feeding system. The processing shown inis performed within one frame, and the same processing is performed in each frame.

143 111 110 1 5 FIG. The power transmission control unitselects antenna elementsincluded in the antenna subsetA one by one, and sequentially transmits a power transmission signal and a power transmission signal of an inverted phase (step S). For example, processing is performed in time slots k to k+4, as shown in.

50 2 The specific deviceA determines angle data from a difference signal (step S).

50 100 3 3 5 FIG. The specific deviceA transmits a beacon signal including the angle data to the power feeding apparatus(step S). The processing in step Sis performed, for example, at the end of time slot k+4, as shown in.

3 4 5 4 5 After step S, the processing in steps SA and SA and the processing in steps SB and SB are performed in parallel.

143 111 110 111 110 4 4 5 FIG. The power transmission control unitcauses multiple antenna elementsincluded in the antenna subsetA to transmit power by random beamforming while maintaining the relationship between optimized power transmission phases, and causes antenna elementsnot included in the antenna subsetA to transmit power by random beamforming (step SA). For example, the power transmission in step SA is performed during the power feeding period after the time slot k+5 in.

50 4 5 4 50 5 FIG. The specific deviceA receives power transmission signals transmitted in step SA (step SA). For example, since the power transmission in step SA is performed during the power feeding period after the time slot k+5 in, the specific deviceA receives the power transmission signals during the power feeding period.

4 5 The processing in steps SA and SA is performed until the end of the frame.

125 111 140 4 The IC chipfor each antenna elementmeasures RSSI of the beacon signal and transfers the RSSI to the controller(step SB).

142 140 111 110 5 111 111 110 The subset selection unitof the controllerselects one or more antenna elementsincluded in the antenna subsetA based on a ranking result of the RSSI (step SB). The antenna elementsselected based on the ranking result are used as antenna elementsincluded in the antenna subsetA in a subsequent frame.

4 5 4 5 6 6 1 When the processing in steps SA and SA and the processing in steps SB and SB are completed, the frame ends (step S). When processing within one frame is completed in step S, the flow returns to step S.

9 FIG. 50 36 111 50 is a diagram for describing an example of a simulation condition. As an example, a simulation is performed for power feeding to the specific deviceA withantenna elementsin a 6×6 array. The specific deviceA moves along an orbit of a dotted circle at a speed of 2.0 m/sec.

300 50 111 110 111 110 111 110 In the simulation for the power feeding system, the simulation is performed for an amount of power received by the specific deviceA, where multiple antenna elementsincluded in the antenna subsetA are selected based on the ranking result of RSSI, power transmission is performed by random beamforming while maintaining the relationship between optimized power transmission phases for the multiple antenna elementsincluded in the antenna subsetA, and power transmission is performed by random beamforming for antenna elementsnot included in the antenna subsetA.

50 111 110 For comparison, a simulation is also performed for the amount of power received by the specific deviceA when power transmission is performed by random beamforming from all (36) antenna elementswithout setting the antenna subsetA.

10 FIG. 10 FIG. 111 is a diagram showing an example of the simulation result for the received power when the power transmission is performed by random beamforming for comparison. In, the horizontal axis represents time, and the vertical axis represents received power (dBm). When the power transmission is performed by random beamforming from all (36) antenna elements, the received power repeatedly fluctuates around 0 (dBm), and shows large variations with time.

11 FIG. 11 FIG. 11 FIG. 11 FIG. 300 111 110 111 110 is a diagram showing an example of the simulation result for the power feeding system. The upper part ofshows temporal changes in the number of antenna elementsincluded in the antenna subsetA. In the upper graph of, the horizontal axis represents time, and the vertical axis represents the number of antenna elementsincluded in the antenna subsetA. In the lower graph of, the horizontal axis represents time, and the vertical axis represents received power (dBm).

11 FIG. 10 FIG. As shown in the lower graph of, the received power is higher than the received power shown in, with many periods of 5 dBm to 6 dBm. A frame period is 50 ms, and a period in which the received power is low at the beginning of each frame is considered to be the optimization period. In the power feeding period after the optimization period ends, received power of 5 dBm to 6 dBm is obtained.

11 FIG. 11 FIG. 111 110 111 110 The upper graph inshows that the number of antenna elementsincluded in the antenna subsetA is 4 to 6. By comparing the upper and lower graphs in, it is confirmed that a greater received power unit is obtained during periods in which there is a larger number of antenna elementsincluded in the antenna subsetA.

300 100 50 100 100 110 111 143 111 50 143 111 111 111 110 111 111 110 50 143 143 A power feeding systemincludes a power feeding apparatus, and a specific deviceA configured to receive power transmission signals transmitted from the power feeding apparatus. The power feeding apparatusincludes an array antennaincluding a plurality of antenna elementsconfigured to transmit power, and a power transmission control unit configured to control phases of the powertransmission signals that are to be transmitted from the plurality of antenna elementsto the specific deviceA, and control power transmission. The power transmission control unitis configured to: select one of a plurality of first antennas included in the plurality of elements antenna; and while transmitting a first power transmission signal having a fixed power transmission phase for a non-selected first antenna (antenna elementnot selected as a target of an optimization process, among antenna elementsin an antenna subsetA) among the plurality of first antennas, perform, while selecting the plurality of first antennas one by one, both a first power transmission process of transmitting a first power transmission signal having a predetermined phase from the selected first antenna (antenna elementselected as the target of the optimization process among the antenna elementsincluded in the antenna subsetA), and a second power transmission process of transmitting a first power transmission signal having an inverted phase obtained by inverting the predetermined phase from the selected first antenna. The specific deviceA is configured to: determine a difference signal between a first combined signal, which combines the first power transmission signal having the predetermined phase and the first power transmission signal having the fixed power transmission phase, the first power transmission signals being both received from the plurality of first antennas in the first power transmission process, and a second combined signal, which combines the first power transmission signal having the inverted phase and the first power transmission signal having the fixed power transmission phase, the first power transmission signals being both received from the plurality of first antennas in the second power transmission process; and transmit the difference signal to the power transmission control unit. The power transmission control unitis configured to control phases of the plurality of first power transmission signals transmitted by the plurality of first antennas, based on a plurality of difference signals obtained by selecting each of the plurality of first antennas. In this arrangement, phases capable of increasing received power of a power receiving device can be promptly set.

300 In this arrangement, it is possible to provide a power feeding systemcapable of promptly setting phases for increasing received power of a power receiving device.

143 111 111 110 300 111 111 110 111 Also, in a second transmission process, a power transmission control unitis configured to set a power transmission phase to an inverted phase for a first antenna that has already been selected in a first transmission process (antenna elementthat has been already selected as a target of an optimization process, among antenna elementsincluded in an antenna subsetA). In this arrangement, it is possible to provide a power feeding systemcapable of promptly setting phases for increasing received power of a power receiving device. For the antenna elementthat has already been selected as the target of the optimization process, among the antenna elementsincluded in the antenna subsetA, by fixing the antenna elementat the inverted phase, no unnecessary process occurs, and phases capable of increasing received power of a power receiving device can be set more promptly.

143 111 110 111 110 111 In a first power transmission process and a second power transmission process, a power transmission control unitis configured to fix power transmission phases for one or more second antennas (antenna elementsnot included in an antenna subsetA) other than the plurality of first antennas (antenna elementsincluded in the antenna subsetA), among the plurality of antenna elements.

111 110 300 In this arrangement, it is possible to determine a plurality of difference signals while suppressing the influence of power transmission signals from one or more second antennas (antenna elementsnot included in the antenna subsetA), to thereby provide a power feeding systemcapable of setting phases for increasing received power of a power receiving device with higher accuracy and more promptly.

300 50 Further, it is possible to provide a power feeding systemcapable of simultaneously achieving both power feeding to a specific power receiving device (specific deviceA) and power feeding to a power receiving device other than the specific power receiving device.

100 142 111 110 111 111 110 111 A power feeding apparatusfurther includes a subset selection unitconfigured to: among the plurality of antennas, select, as the plurality of first antennas (antenna elementsincluded in an antenna subsetA), multiple antenna elementshaving reception strength of a signal transmitted from a power receiving device that is equal to or greater than a predetermined strength, and select, as one or more second antennas (antenna elementsnot included in the antenna subsetA), multiple antenna elementshaving the reception strength less than the predetermined strength.

111 111 110 50 110 111 50 In this arrangement, a plurality of antenna elementshaving reception strength that is equal to or greater than a predetermined strength (having a ranking that is equal to or greater than a predetermined rank) can be selected as antenna elementsincluded in an antenna subsetA, and power can be efficiently fed to a specific deviceA using an antenna subsetA that is composed of multiple antenna elementsthat are close to the specific deviceA.

300 Moreover, a signal transmitted from a power receiving device is a signal representing a difference signal. In this arrangement, transmission of angle data, and RSSI for ranking measurement can be performed simultaneously by using a signal including the angle data representing the difference signal. Thus, a power feeding systemcapable of promptly and efficiently setting phases for increasing received power of a power receiving device can be provided.

143 111 110 50 111 142 Further, a power transmission control unitis configured to repeatedly perform a frame process including a preparation period (optimization period) for performing a first transmission process and a second transmission process; and a power transmission period (power feeding period) for transmitting power from a plurality of first antennas (antenna elementsincluded in an antenna subsetA) to a specific deviceA by controlling phases of a plurality of first power transmission signals transmitted from the plurality of first antennas based on a plurality of difference signals, and to use, among a plurality of antenna elements, the plurality of first antennas that are selected by an antenna selection unitbased on reception strength (RSSI) of signals (beacon signals including angle data) representing the difference signals, as the plurality of first antennas for a subsequent frame of a current frame.

111 110 In this arrangement, antenna elementsincluded in the antenna subsetA in a subsequent frame can be selected based on reception strength (RSSI) of signals representing difference signals (beacon signals including angle data).

50 300 50 50 A specific deviceA is movable. In this arrangement, it is possible to provide a power feeding systemcapable of promptly setting phases for increasing received power of the specific deviceA, even when phases of received power transmission signals change as the specific deviceA moves.

143 50 50 50 Furthermore, a power transmission control unitis configured to control power transmission phases of a plurality of first power transmission signals transmitted by a plurality of first antennas such that power reception phases of the plurality of first power transmission signals received by a specific deviceA from the plurality of first antennas are aligned based on a plurality of difference signals. In this arrangement, the power transmission phases of the first power transmission signals can be controlled such that received power of the specific deviceA is maximized, and the received power of the specific deviceA can be reliably increased.

100 50 111 143 111 50 143 111 111 111 110 111 111 110 50 50 A power feeding apparatusfor transmitting power transmission signals to a specific deviceA includes an array antenna including a plurality of antenna elementsconfigured to transmit power, and a power transmission control unitconfigured to control phases of the power transmission signals that are to be transmitted from the plurality of antenna elementsto the specific deviceA, and control power transmission. The power transmission control unitis configured to select one of a plurality of first antennas included in the plurality of antenna elements; while transmitting a first power transmission signal having a fixed power transmission phase for a non-selected first antenna (antenna elementnot selected as a target of an optimization process, among antenna elementsincluded in an antenna subsetA) among the plurality of first antennas, perform, while selecting the plurality of first antennas one by one, both a first power transmission process of transmitting a first power transmission signal having a predetermined phase from the selected first antenna (antenna elementselected as the target of the optimization process among the antenna elementsincluded in the antenna subsetA), and a second power transmission process of transmitting a first power transmission signal having an inverted phase obtained by inverting the predetermined phase from the selected first antenna; and control phases of the plurality of first power transmission signals transmitted by the plurality of first antennas, based on a plurality of difference signals obtained by selecting each of the plurality of first antennas. Each of the plurality of difference signals is a difference signal between a first combined signal, which combines the first power transmission signal having the predetermined phase and the first power transmission signal having the fixed power transmission phase, the first power transmission signals being both received by a specific deviceA from the plurality of first antennas in the first power transmission process, and a second combined signal, which combines the first power transmission signal having the inverted phase and the first power transmission signal having the fixed power transmission phase, the first power transmission signals being both received by the specific deviceA from the plurality of first antennas in the second power transmission process. In this arrangement, phases capable of increasing received power of a power receiving device can be promptly set.

100 In this arrangement, a power feeding apparatuscapable of promptly setting phases for increasing received power of a power receiving device can be provided.

300 100 50 100 100 110 111 143 111 50 143 111 selecting one of a plurality of first antennas included in the plurality of antenna elements, 111 111 110 111 111 110 while transmitting a first power transmission signal having a fixed power transmission phase for a non-selected first antenna (antenna elementnot selected as a target of an optimization process, among antenna elementsincluded in an antenna subsetA) among the plurality of first antennas, performing, while selecting the plurality of first antennas one by one, both a first power transmission process of transmitting a first power transmission signal having a predetermined phase from the selected first antenna (antenna elementselected as the target of the optimization process, among the antenna elementsincluded in the antenna subsetA); and a second power transmission process of transmitting a first power transmission signal having an inverted phase obtained by inverting the predetermined phase from the selected first antenna; by the power transmission control unit, 50 determining a difference signal between a first combined signal, which combines the first power transmission signal having the predetermined phase and the first power transmission signal having the fixed power transmission phase, the first power transmission signals being both received from the plurality of first antennas in the first power transmission process, and a second combined signal, which combines the first power transmission signal having the inverted phase and the first power transmission signal having the fixed power transmission phase, the first power transmission signals being both received from the plurality of first antennas in the second power transmission process, and 143 transmitting the difference signal to the power transmission control unit; and by the specific deviceA, 143 by the power transmission control unit, controlling phases of the plurality of first power transmission signals transmitted by the plurality of first antennas, based on a plurality of difference signals obtained by selecting each of the plurality of first antennas. With this approach, phases capable of increasing received power of a power receiving device can be promptly set. A power feeding method is executed by a power feeding systemincluding a power feeding apparatus, and a specific deviceA configured to receive power transmission signals transmitted from the power feeding apparatus, and the power feeding apparatusincludes an array antennaincluding a plurality of antenna elementsconfigured to transmit power, and includes a power transmission control unitconfigured to control phases of the power transmission signals that are to be transmitted from the plurality of antenna elementsto the specific deviceA, and control power transmission. The power feeding method includes:

With this approach, a power feeding method capable of promptly setting phases for increasing received power of a power receiving device can be provided.

12 FIG. 5 FIG. 12 FIG. 12 FIG. 300 110 111 111 110 110 111 is a diagram for describing an example of the optimization process in the power feeding systemin a modification of the embodiment. Similar to,shows the optimization period, power feeding period, and time slots in one frame. As an example, it is assumed that the antenna subsetA includes four antenna elements. The optimization process includes a number of time slots that is twice the number of antenna elementsincluded in the antenna subsetA. In, since the antenna subsetA includes four antenna elements, the optimization period includes eight time slots (k to k+7). Also, the power feeding period starts from time slot k+8 and is longer than the optimization period. In this example, the power feeding period is shown in a simplified manner.

143 111 111 110 In the optimization process in the modification, the power transmission control unitsets power transmission phases for non-selected first antenna (antenna elementsnot selected as targets of the optimization process, among antenna elementsincluded in the antenna subsetA) at the same value in a first transmission process and a second transmission process.

1 1 1 2 2 2 More specifically, an process optimization of transmitting a power transmission signal by setting the power transmission phase for the antenna element mat φm+π (an example of a second power transmission process for the antenna element m), and an optimization process of transmitting a power transmission signal by setting the power transmission phase for the antenna element mat φm(an example of a first power transmission process for the antenna element m) are performed in separate time slots k+1 and k+2.

2 2 2 3 3 3 In the optimization process in the modification, an optimization process of transmitting a power transmission signal by setting the power transmission phase for the antenna element mat φm+π (an example of a second power transmission process for the antenna element m), and an optimization of process transmitting a power transmission signal by setting the power transmission phase for the antenna element mat φm(an example of a first power transmission process for the antenna element m) are performed in separate time slots k+3 and k+4.

3 3 3 4 4 In the optimization process in the modification, an optimization process of transmitting a power transmission signal by setting the power transmission phase for the antenna element mat φm+π (an example of a second power transmission process for the antenna element m), and an optimization process of transmitting a power transmission signal by setting the power transmission phase of the antenna element mat φm(an example of a first power transmission process for the antenna element ma) are performed in separate time slots k+5 and k+6.

4 4 4 Then, an optimization process of transmitting a power transmission signal by setting the power transmission phase for the antenna element mat φm+π (an example of a second power transmission process for the antenna element m) is performed in time slot k+7.

5 FIG. In this arrangement, the optimization process in the modification is slightly longer in required time than the optimization process shown in.

12 FIG. 1 4 1 4 As shown in, after power transmission phases for the antenna elements mto mare optimized, these power transmission phases are fixed at the optimized power transmission phases and remain fixed during the power feeding period. However, when entering the power feeding period, random beamforming may be performed while maintaining the relationship between the optimized power transmission phases. The optimized power transmission phases for the antenna elements mto mare examples of phases based on difference signals.

13 13 FIGS.A toE 50 50 1 4 are diagrams for describing power reception phases of power transmission signals received by the specific deviceA in the modification of the embodiment. The I-axis is the real axis, and the Q-axis is the imaginary axis. Four vectors (1) to (4) represent the power transmission signals received by the specific deviceA from the antenna elements mto min vector form.

1 4 1 4 1 4 1 4 51 It is assumed that the power transmission phases for the antenna elements mto mare φmto φm, respectively, and that remainders (fraction parts) obtained by dividing distances between the antenna elements mto mand the antennaby a wavelength are ξmto ξm, respectively.

13 FIG.A 13 FIG.A 50 1 4 1 1 2 2 3 3 4 4 As shown in, the power reception phases of the power transmission signals received by the specific deviceA from the antenna elements mto min time slot k are ξm+φm, ξm+φm, ξm+φm, and ξm+φm, respectively. The four vectors (1) to (4) are as shown in.

50 1 4 1 1 2 2 3 3 4 4 13 FIG.A The power reception phases of the power transmission signals received by the specific deviceA from the antenna elements mto min time slot k+1 are ξm+φm+π, ξm+φm, ξm+φm, and ξm+φm, respectively. The four vectors (1) to (4) are as shown in, and the vector (1) is oriented in the opposite direction compared to the time slot k.

56 57 100 58 When the four vectors (1) to (4) in time slot k+1 are subtracted from the four vectors (1) to (4) in the time slot k, vectors (2) to (4) are eliminated, and only a vector (1A), which has twice the magnitude of the vector (1), remains as the difference. A signal representing the vector (1A) is a difference signal, and is obtained by the calculation unitthrough subtraction processing. An angle of the vector (1A) with respect to the I-axis is α1. The angle α1 is obtained by the angle conversion unit. At this point, a beacon signal including the angle α1 is transmitted to the power feeding apparatusvia the communication unit. The four vectors (1) to (4) in the time slot k are an example of a first combined signal, and the four vectors (1) to (4) in the time slot k+1 are an example of a second combined signal.

13 FIG.B 13 FIG.B 1 2 4 2 2 3 3 4 4 1 50 100 58 50 As shown in, in time slot k+2, the power reception phase of the power transmission signal received from the antenna element mby the specific deviceA is 0 degrees, and power reception phases of power transmission signals received from the antenna elements mto mare m+φm, ξm+φm, and ξm+φm, respectively. The four vectors (1) to (4) are as shown in. When a beacon signal including the angle α1 is not transmitted to the power feeding apparatusvia the communication unitin the time slot k+1, the power reception phase of the power transmission signal received from the antenna element mby the specific deviceA in the time slot k+2 is α1 degrees.

1 2 4 2 2 3 3 4 4 50 13 FIG.B The power reception phase of the power transmission signal received from the antenna element mby the specific deviceA in time slot k+3 is 0 degrees, and power reception phases of power transmission signals received from the antenna elements mto mare ξm+φm+π, ξm+φm, and ξm+φm, respectively. The four vectors (1) to (4) are as shown in, and the vector (2) is oriented in the opposite direction compared to the time slot k+2.

56 57 When the four vectors (1) to (4) in time slot k+3 are subtracted from the four vectors (1) to (4) in the time slot k+2, vectors (1), (3), and (4) are eliminated, and only a vector (2A), which has twice the magnitude of the vector (2), remains as the difference. A signal representing the vector (2A) is a difference signal, and is obtained by the calculation unitthrough subtraction processing. An angle of the vector (2A) with respect to the I-axis is set at α2. The angle α2 is obtained by the angle conversion unit. The four vectors (1) to (4) in the time slot k+2 are an example of a first combined signal, and the four vectors (1) to (4) in the time slot k+3 are an example of a second combined signal.

13 FIG.C 13 FIG.C 50 100 58 50 1 2 3 4 3 3 4 4 1 2 As shown in, in time slot k+4, power reception phases of power transmission signals received by the specific deviceA from the antenna elements mand mare 0 degrees, and power reception phases of power transmission signals received by the antenna elements mand mare ξm+φmand ξm+φm, respectively. The four vectors (1) to (4) are as shown in. When beacon signals including the angles α1 and α2 are not transmitted to the power feeding apparatusvia the communication unitin time slots k+1 and k+3, the power reception phases of the power transmission signals received by the specific deviceA from the antenna elements mand min the time slot k+4 are α1 degrees and α2 degrees.

50 1 2 3 4 3 3 4 4 13 FIG.C In time slot k+5, power reception phases of power transmission signals received by the specific deviceA from the antenna elements mand mare 0 degrees, and power reception phases of power transmission signals received by the antenna elements mand mare ξm+φm+π and ξm+φm, respectively. The four vectors (1) to (4) are as shown in, and the vector (3) is oriented in the opposite direction compared to the time slot k+4.

56 57 When the four vectors (1) to (4) in the time slot k+5 are subtracted from the four vectors (1) to (4) in the time slot k+4, vectors (1), (2), and (4) are eliminated, and only a vector (3A), which has twice the magnitude of the vector (3), remains as the difference. A signal representing the vector (3A) is a difference signal, and is obtained by the calculation unitthrough subtraction processing. An angle of the vector (3A) with respect to the I-axis is α3. The angle α3 is obtained by the angle conversion unit. The four vectors (1) to (4) in the time slot k+4 are an example of a first combined signal, and the four vectors (1) to (4) in the time slot k+5 are an example of a second combined signal.

13 FIG.D 13 FIG.D 1 3 4 4 4 1 3 50 100 58 50 As shown in, in time slot k+6, power reception phases of power transmission signals received from the antenna elements mto mby the specific deviceA are 0 degrees, and the power reception phase of the power transmission signal received from the antenna element mis ξm+φm. The four vectors (1) to (4) are as shown in. When beacon signals including the angles α1 to α3 are not transmitted to the power feeding apparatusvia the communication unitin the time slots k+1, k+3, and k+5, the power reception phases of the power transmission signals received from the antenna elements mto mby the specific deviceA in the time slot k+6 are α1 to α3 degrees, respectively.

1 3 4 4 4 50 13 FIG.D The power reception phases of the power transmission signals received from the antenna elements mto mby the specific deviceA in time slot k+7 are 0 degrees, and the power reception phase of the power transmission signal received from the antenna element mis ξm+φm+π. The four vectors (1) to (4) are as shown in, and the vector (4) is oriented in the opposite direction compared to the time slot k+6.

56 When the four vectors (1) to (4) in the time slot k+7 are subtracted from the four vectors (1) to (4) in the time slot k+6, vectors (1) to (3) are eliminated, and only a vector (4A), which has twice the magnitude of the vector (4), remains as the difference. A signal representing the vector (4A) is a difference signal, and is obtained by the calculation unitthrough subtraction processing. The four vectors (1) to (4) in the time slot k+6 are an example of a first combined signal, and the four vectors (1) to (4) in the time slot k+7 are an example of a second combined signal.

57 58 100 The angle of the vector (4A) with respect to the I-axis is α4. The angle α4 is obtained by the angle conversion unit. The communication unittransmits a beacon signal including the angle α4 to the power feeding apparatus.

100 58 58 100 100 If the beacon signals including the angles α1 to α3 are not transmitted to the power feeding apparatusvia the communication unitin the time slots k+1, k+3, and k+5, the communication unitmay transmit angle data representing the angles α1 to α4 to the power feeding apparatusat the end of the time slot k+7. RSSI measurement for ranking is sufficient to be performed when the power feeding apparatusreceives any beacon signal.

143 13 FIG.E 13 FIG.E The power transmission control unitadjusts the phases of the vectors (1) to (4) to adjust the angles α1 to α4 in time slot k+8. As a result, the vectors (1) to (4) can be aligned as shown in. In, the vectors (1) to (4) are aligned along the I-axis as an example, but may have an angle greater than 0 degrees with respect to the I-axis.

50 In this arrangement, the vectors (1) to (4) can be aligned. That is, the received power of the specific deviceA can be maximized.

1 4 1 4 13 FIG.E 111 110 111 In the feeding period after time slot k+8, power transmission may be performed in a state where the four power transmission phases for the antenna elements mto moptimized as shown inare maintained. In the feeding period, random beamforming may be performed in a state where the relationship between the four power transmission phases for the antenna elements mto mis maintained, such that the angles for the vectors (1) to (4) are aligned. In addition, for multiple antenna elementsnot included in the antenna subsetA, random beamforming is performed without setting any particular relationship between power transmission phases of the multiple antenna elements.

14 FIG. 14 FIG. 14 FIG. 14 FIG. 300 111 110 111 110 is a diagram showing an example of the simulation result for the feeding systemin the modification of the embodiment. The upper part ofshows temporal changes in the number of antenna elementsincluded in the antenna subsetA. In the upper graph of, the horizontal axis represents time, and the vertical axis represents the number of antenna elementsincluded in the antenna subsetA. In the lower graph of, the horizontal axis represents time, and the vertical axis represents received power (dBm).

14 FIG. 10 FIG. As shown in the lower graph of, the received power is higher than the received power shown in, with many periods of 5 dBm to 6 dBm. The frame period is 50 ms, and a period of low received power at the beginning of each frame is considered to be an optimization period. In the power feeding period after the optimization period ends, the received power of 5 dBm to 6 dBm is obtained.

14 FIG. 14 FIG. 111 110 111 110 The upper graph ofshows that the number of antenna elementsincluded in the antenna subsetA is 4 to 6. By comparing the upper and lower graphs of, it is confirmed that the larger received power is obtained during periods in which a larger number of antenna elementsincluded in the antenna subsetA is obtained.

300 Even in the modification of the embodiment, phases capable of increasing received power of a power receiving device can be promptly set. In this arrangement, the power feeding systemin the modification of the embodiment that is capable of promptly setting phases for increasing the received power of the power receiving device can be provided.

300 50 In addition, it is possible to provide the power feeding systemin the modification of the embodiment that can simultaneously achieve both power feeding to a specific power receiving device (specific deviceA) requiring a large amount of received power, and power feeding to a power receiving device other than the specific power receiving device.

The power feeding system, the power feeding apparatus, and the power feeding method according to the exemplary embodiments of the present invention have been described above, but the present invention is not limited to the specifically disclosed embodiments, and various modifications and changes can be made without departing from the scope of the claims.

This international application claims to priority Japanese patent application 2022-163333, filed on Oct. 11, 2022, the entire contents of which are incorporated herein by reference.

10 region 50 device 50 A specific device 50 B non-specified device 51 antenna SW switch 52 control unit 53 RF/DC conversion unit 54 battery 55 orthogonal detection unit 56 calculation unit 57 angle conversion unit 58 communication unit 100 power feeding apparatus 110 array antenna 110 A antenna subset 111 antenna element 120 phase shifter 125 IC chip 130 microwave generator 140 controller 141 main control unit 142 subset selection unit 143 power transmission control unit 144 memory